Hello everyone!
I'm growing carnivorous plants indoors on a 1.5x4ft wire rack and am interested in learning more about LED strips. I'm aiming to put the lights somewhere between 12 and 24 inches above the plants and I'm hoping to achieve a PPFD between 200 and 400 umol/s/m^2 (higher would be fine but not necessary) throughout the growing surface. Some of my plants prefer 200 while some prefer 400 so some variation is OK.
Are there any brands/models of LED strips that you recommend looking into? How many strips would I need to buy? Nowadays, how does their efficiency compare with COBs?
All advice appreciated!
LED strips for a 4x1.5ft area
Thank you! LED strips seem easier to work with than COBs so that's good news.
By what I can tell, the Bridgelux EB Gen3 strips are often recommended here. Are there any other type of strips worth considering given that I am purely interested in their ability to grow plants?
How many strips would I need to obtain a PPFD 200-400 umol/s/m^2? Are there any calculations worth learning or is experience the only way to tell?
Is it more typical to power multiple LED strips in series or parallel?
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The_Mouse_Police
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On an open shelf, I would speculate around 120-150W, but could be off a bit, for such a distance (also, with more strips, the drop over distance gets closer to linear than exponential). The less current each strip uses, the more efficient it runs, and the cooler it is, the more efficient it runs. The harder you drive them, the more cooling you need.
Running them harder also reduces their lifespan, especially of the phosphors. Given that the tech is mature enough that we're getting ~5% efficicacy improvements per year, now, I'm of the mind that planning to keep them, "healthy," is a good idea, running them softer than they rated for. The energy efficiency of LEDs two or three years from now will likely not be anywhere near enough to justify replacing a working ~200lm/W rig.
I haven't seen anything from actual builds, so just going by the data sheet, I would speculate 10W per 2ft strip to be pretty reasonable in open air (not in a tent), with no added cooling. 20W would likely require added heatsinking, but probably no more than some U-channel and thermal adhesive tape, if there is a fan nearby. It can be difficult to accurately predict temperatures, not using heatsinks with known thermal specs. Using U-channel, L-channel, aluminum sheet, wide enough standard extrusions, etc., though, let's you include some cooling as part of making a fixture, with said fixture being easy to make with common tools. If you drive them at or under their rated currents, it's usually plenty good enough.
Running them harder also reduces their lifespan, especially of the phosphors. Given that the tech is mature enough that we're getting ~5% efficicacy improvements per year, now, I'm of the mind that planning to keep them, "healthy," is a good idea, running them softer than they rated for. The energy efficiency of LEDs two or three years from now will likely not be anywhere near enough to justify replacing a working ~200lm/W rig.
I haven't seen anything from actual builds, so just going by the data sheet, I would speculate 10W per 2ft strip to be pretty reasonable in open air (not in a tent), with no added cooling. 20W would likely require added heatsinking, but probably no more than some U-channel and thermal adhesive tape, if there is a fan nearby. It can be difficult to accurately predict temperatures, not using heatsinks with known thermal specs. Using U-channel, L-channel, aluminum sheet, wide enough standard extrusions, etc., though, let's you include some cooling as part of making a fixture, with said fixture being easy to make with common tools. If you drive them at or under their rated currents, it's usually plenty good enough.
Maybe I could start with about 6 strips and then expand to 12 if I end up needing more light. This approach would likely save energy as well since I wouldn't be using the full grow space from day 1. Getting a dimmable driver would also mean I have some flexibility in increasing/decreasing light intensity as needed.
Really cool idea to use U-channels for heat dissipation. I like it!
Should I pick a ~20 V driver and connect the LED strips in parallel or is it better to go for a constant current driver with a max voltage large enough to accommodate all strips in series?
Really cool idea to use U-channels for heat dissipation. I like it!
Should I pick a ~20 V driver and connect the LED strips in parallel or is it better to go for a constant current driver with a max voltage large enough to accommodate all strips in series?
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The_Mouse_Police
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CC makes dimming a little easier, but the voltage ranges tend to be geared towards several high power COBs in series, so it can be tedious to find one with the right voltage range and current for your setup, with 20-24V strips. CV is a little ticky when it comes to fine tuning the output current, but is easier to deal with for changing the configuration. Having both, I would preferably choose a CV AB-suffix Meanwell, if it were available at a suitable voltage (rare for 20V and 42V, from what I've seen, FI).
I would still buy a 24 or 48v driver, you will use a little more power with them but a driver lasts 10 years or more but strips you change every few years, there is alot more options for 24 and 48v products around. It will probably work out to be around $5 of extra electricity per year going for a 24V driver as opposed to a 20V driver but when it comes time to upgrade you will have alot more options of strips or boards to choose from. The meanwell XLG range is dirt cheap and decent efficiency
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How do you fine tune the output current when using CV?The_Mouse_Police wrote: ↑Sat Sep 14, 2019 11:59 pmCV is a little ticky when it comes to fine tuning the output current, but is easier to deal with for changing the configuration.
Also, I read that, when using CV, the current of the LEDs can change as the lights heat up. Could that end up causing issues?
Having more options available for future upgrades is a great idea.TEKNIK wrote: ↑Sun Sep 15, 2019 12:14 amI would still buy a 24 or 48v driver, you will use a little more power with them but a driver lasts 10 years or more but strips you change every few years, there is alot more options for 24 and 48v products around. It will probably work out to be around $5 of extra electricity per year going for a 24V driver as opposed to a 20V driver but when it comes time to upgrade you will have alot more options of strips or boards to choose from. The meanwell XLG range is dirt cheap and decent efficiency
But by what I understand, if I get a 24v CV HLG driver, even if it's type A, I'd only be able to lower the voltage to ~22v, which is too high to drive the LED strips at a reasonable current. How would I be able to make a 24v driver work with these LED strips?
Regarding tuning, they way you work out how hard the leds will run is off the current the driver puts out. If it's a 24v 10amp driver e.g. HLG 240A and you ran 10 strips then each strip would get 1 amp each, For the bridgelux strips they run best at about 700mA so for use on a 240W driver you would want to use 14 2 foot strips.
A HLG 240-24A driver will run from 12V to 24V, the bridgelux strips use around 19V @700mA, voltage will drop a bit probably to 18V once they heat up bit your driver will run that easily. Voltage drops not current when leds get hot.
A cheap buy is the XLG 200-24 to run bridgelux strips.
Regarding voltage adjustment on an A driver, most people don't use this function correctly, you can set it up as a saftey feature if one or more strips drop out, most people don't do this or understand it. You can adjust the voltage down in an A or AB driver but it won't go low enough to take advantage of the saftey feature, because you are running so many strips this isn't a big deal as you would likely notice a strip not working and fix it before it becomes a major issue. If it's a concern then add in a few extra strips as they are cheap enough.
A HLG 240-24A driver will run from 12V to 24V, the bridgelux strips use around 19V @700mA, voltage will drop a bit probably to 18V once they heat up bit your driver will run that easily. Voltage drops not current when leds get hot.
A cheap buy is the XLG 200-24 to run bridgelux strips.
Regarding voltage adjustment on an A driver, most people don't use this function correctly, you can set it up as a saftey feature if one or more strips drop out, most people don't do this or understand it. You can adjust the voltage down in an A or AB driver but it won't go low enough to take advantage of the saftey feature, because you are running so many strips this isn't a big deal as you would likely notice a strip not working and fix it before it becomes a major issue. If it's a concern then add in a few extra strips as they are cheap enough.
Find me on Instagram led_teknik
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The_Mouse_Police
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The A adjustment will also let you tune your max output between drivers. For DIY, that is best used with an AB driver, dimming via voltage, PWM, or a shared pot. One advantage, simplifying things for a fixed setup, to dim multiple CC drivers, is that thee drivers will already be within a couple percent of each other's output power, at 100% output, before dimming.
As far as output on a CV, you're mostly getting close enough, extrapolating from the data sheet. To get fairly accurate, you could use a Kill-A-Watt, FI, and use the efficiency to figure out if you're right. IE, [measured Watts]*[effciency at expected power]: 125W*0.91=114W (efficiency is +/-1% across the top 20% or more, generally, so a guess is usually fine). Then divide by voltage measured by a multimeter, if you want current. Or just divide by strip count, for power per strip.
Now, here's where a CV is nice for DIY, as anecdote. I got an ELG240-C1400B and ELG-240-C2100B, for some PFD and HLG panels on that same wire shelf. Setup couldn't have been easier. But, now, I want to use different devices, and have to try to come up with serious and parallel arrangements that are wasteful for my strips and stars (and wallet), or awkward to figure out how to mount. An adjustable 36V out driver would have been very easy to repurpose, even working with some 20V strips.
As far as output on a CV, you're mostly getting close enough, extrapolating from the data sheet. To get fairly accurate, you could use a Kill-A-Watt, FI, and use the efficiency to figure out if you're right. IE, [measured Watts]*[effciency at expected power]: 125W*0.91=114W (efficiency is +/-1% across the top 20% or more, generally, so a guess is usually fine). Then divide by voltage measured by a multimeter, if you want current. Or just divide by strip count, for power per strip.
Now, here's where a CV is nice for DIY, as anecdote. I got an ELG240-C1400B and ELG-240-C2100B, for some PFD and HLG panels on that same wire shelf. Setup couldn't have been easier. But, now, I want to use different devices, and have to try to come up with serious and parallel arrangements that are wasteful for my strips and stars (and wallet), or awkward to figure out how to mount. An adjustable 36V out driver would have been very easy to repurpose, even working with some 20V strips.